The present invention relates generally to video interfaces, and more particularly to a user interface for digital video magnification.
Surveillance systems commonly receive digital video from one or more cameras, and play back that video on screens or displays of one or more user stations, either in real time or from a recorder or archive. Such video is commonly displayed via a user interface which may allow users to control the pan, tilt, or zoom of the camera. For archived footage, user interfaces typically also allow users to advance or scan backwards or forwards through video at multiple speeds. Zooming allows a user to focus on a small region of an image or video sequence of images, by providing an expanded image of a reduced camera field of view. Many conventional methods exist for both optical and digital (software-based) zoom. By zooming in on one feature, however, users limit their ability to observe surrounding features outside of the resulting reduced field of view. To prevent this information from being lost, some user interfaces for surveillance systems provide a “Picture in a Picture” image, wherein small reference image of the full camera field of view overlays a larger, zoomed image. This smaller, un-zoomed image is sometimes marked to indicate the region visible in the larger, zoomed image. “Picture in a Picture” interfaces allow users to view details in a zoomed-in area, while retaining the ability to see the wider field of view of the camera on the same screen.
“Picture in a Picture” interfaces do not provide a perfect solution. Some portion of the zoomed image is covered by the un-zoomed reference image, obscuring a portion of the zoomed image. Un-zoomed reference images in “Picture in a Picture” interfaces are typically very small, and correspondingly lose detail. Additionally, identifying the location of a zoomed image relative to an un-zoomed reference image requires eye movement between the two images, which can be disorienting. Conventional “Picture in a Picture” interfaces scale zoomed images linearly.